Re: [Xen-devel] [PATCH v5 3/5] xen: Identify panic and reboot/halt functions as noreturn

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2014-02-28 at 18:07 +0000, Andrew Cooper wrote:
> On an x86 build (GCC Debian 4.7.2-5), this substantially reduces the size of
> .text and .init.text sections.
> 
> Experimentally, even in a non-debug build, GCC uses `call` rather than `jmp`
> so there should be no impact on any stack trace generation.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Acked-by: Keir Fraser <keir@xxxxxxx>
> Reviewed-by: Jan Beulich <JBeulich@xxxxxxxx>

Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

> CC: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
> Acked-by: Tim Deegan <tim@xxxxxxx>
> ---
>  xen/arch/arm/shutdown.c         |    2 +-
>  xen/arch/x86/cpu/mcheck/mce.h   |    2 +-
>  xen/arch/x86/shutdown.c         |    2 +-
>  xen/common/shutdown.c           |    2 +-
>  xen/include/asm-arm/smp.h       |    2 +-
>  xen/include/asm-x86/processor.h |    2 +-
>  xen/include/xen/lib.h           |    2 +-
>  xen/include/xen/shutdown.h      |    8 +++++---
>  8 files changed, 12 insertions(+), 10 deletions(-)
> 
> diff --git a/xen/arch/arm/shutdown.c b/xen/arch/arm/shutdown.c
> index 767cc12..adc0529 100644
> --- a/xen/arch/arm/shutdown.c
> +++ b/xen/arch/arm/shutdown.c
> @@ -11,7 +11,7 @@ static void raw_machine_reset(void)
>      platform_reset();
>  }
>  
> -static void halt_this_cpu(void *arg)
> +static void noreturn halt_this_cpu(void *arg)
>  {
>      stop_cpu();
>  }
> diff --git a/xen/arch/x86/cpu/mcheck/mce.h b/xen/arch/x86/cpu/mcheck/mce.h
> index cbd123d..33bd1ab 100644
> --- a/xen/arch/x86/cpu/mcheck/mce.h
> +++ b/xen/arch/x86/cpu/mcheck/mce.h
> @@ -57,7 +57,7 @@ int mce_available(struct cpuinfo_x86 *c);
>  unsigned int mce_firstbank(struct cpuinfo_x86 *c);
>  /* Helper functions used for collecting error telemetry */
>  struct mc_info *x86_mcinfo_getptr(void);
> -void mc_panic(char *s);
> +void noreturn mc_panic(char *s);
>  void x86_mc_get_cpu_info(unsigned, uint32_t *, uint16_t *, uint16_t *,
>                        uint32_t *, uint32_t *, uint32_t *, uint32_t *);
>  
> diff --git a/xen/arch/x86/shutdown.c b/xen/arch/x86/shutdown.c
> index 6143c40..827515d 100644
> --- a/xen/arch/x86/shutdown.c
> +++ b/xen/arch/x86/shutdown.c
> @@ -452,7 +452,7 @@ static int __init reboot_init(void)
>  }
>  __initcall(reboot_init);
>  
> -static void __machine_restart(void *pdelay)
> +static void noreturn __machine_restart(void *pdelay)
>  {
>      machine_restart(*(unsigned int *)pdelay);
>  }
> diff --git a/xen/common/shutdown.c b/xen/common/shutdown.c
> index 9bccd34..fadb69b 100644
> --- a/xen/common/shutdown.c
> +++ b/xen/common/shutdown.c
> @@ -17,7 +17,7 @@
>  bool_t __read_mostly opt_noreboot;
>  boolean_param("noreboot", opt_noreboot);
>  
> -static void maybe_reboot(void)
> +static void noreturn maybe_reboot(void)
>  {
>      if ( opt_noreboot )
>      {
> diff --git a/xen/include/asm-arm/smp.h b/xen/include/asm-arm/smp.h
> index a1de03c..91b1e52 100644
> --- a/xen/include/asm-arm/smp.h
> +++ b/xen/include/asm-arm/smp.h
> @@ -15,7 +15,7 @@ DECLARE_PER_CPU(cpumask_var_t, cpu_core_mask);
>  
>  #define raw_smp_processor_id() (get_processor_id())
>  
> -extern void stop_cpu(void);
> +extern void noreturn stop_cpu(void);
>  
>  extern int arch_smp_init(void);
>  extern int arch_cpu_init(int cpu, struct dt_device_node *dn);
> diff --git a/xen/include/asm-x86/processor.h b/xen/include/asm-x86/processor.h
> index 4da545e..498d8a7 100644
> --- a/xen/include/asm-x86/processor.h
> +++ b/xen/include/asm-x86/processor.h
> @@ -515,7 +515,7 @@ void show_registers(struct cpu_user_regs *regs);
>  void show_execution_state(struct cpu_user_regs *regs);
>  #define dump_execution_state() run_in_exception_handler(show_execution_state)
>  void show_page_walk(unsigned long addr);
> -void fatal_trap(int trapnr, struct cpu_user_regs *regs);
> +void noreturn fatal_trap(int trapnr, struct cpu_user_regs *regs);
>  
>  void compat_show_guest_stack(struct vcpu *, struct cpu_user_regs *, int 
> lines);
>  
> diff --git a/xen/include/xen/lib.h b/xen/include/xen/lib.h
> index 0d1a5d3..1369b2b 100644
> --- a/xen/include/xen/lib.h
> +++ b/xen/include/xen/lib.h
> @@ -87,7 +87,7 @@ extern void printk(const char *format, ...)
>      __attribute__ ((format (printf, 1, 2)));
>  extern void guest_printk(const struct domain *d, const char *format, ...)
>      __attribute__ ((format (printf, 2, 3)));
> -extern void panic(const char *format, ...)
> +extern void noreturn panic(const char *format, ...)
>      __attribute__ ((format (printf, 1, 2)));
>  extern long vm_assist(struct domain *, unsigned int, unsigned int);
>  extern int __printk_ratelimit(int ratelimit_ms, int ratelimit_burst);
> diff --git a/xen/include/xen/shutdown.h b/xen/include/xen/shutdown.h
> index 2bee748..f04905b 100644
> --- a/xen/include/xen/shutdown.h
> +++ b/xen/include/xen/shutdown.h
> @@ -1,13 +1,15 @@
>  #ifndef __XEN_SHUTDOWN_H__
>  #define __XEN_SHUTDOWN_H__
>  
> +#include <xen/compiler.h>
> +
>  /* opt_noreboot: If true, machine will need manual reset on error. */
>  extern bool_t opt_noreboot;
>  
> -void dom0_shutdown(u8 reason);
> +void noreturn dom0_shutdown(u8 reason);
>  
> -void machine_restart(unsigned int delay_millisecs);
> -void machine_halt(void);
> +void noreturn machine_restart(unsigned int delay_millisecs);
> +void noreturn machine_halt(void);
>  void machine_power_off(void);
>  
>  #endif /* __XEN_SHUTDOWN_H__ */



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